1gl_wtriangle(3)               Svgalib User Manual              gl_wtriangle(3)
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NAME

6       gl_wtriangle - draw a shadowed pixmap mapped on a triangle
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SYNOPSIS

10       #include <triangle.h>
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12       typedef struct {
13           unsigned char *bitmap1;
14           unsigned char *bitmap2;
15           int bf;
16       } TD_tridata;
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18       void  gl_wtriangle(int  x0,  int y0, int xd0, int yd0, int z0 , int x1,
19       int y1, int xd1, int yd1, int z1 , int x2, int y2, int  xd2,  int  yd2,
20       int z2, TD_tridata *tri);
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DESCRIPTION

24       Draws  a  triangle  at points 0, 1, 2 by mapping the pixmaps defined in
25       the TD_triangle structure into the triangle.
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27       The xd and yd values represent the triangle on the bitmap and the x and
28       y  values  represent the triangle on the screen. The z values represent
29       an additional value which will be added to the color that is looked  up
30       from the pixmap data. Once again, if the current context is more than 8
31       bits then the result is interpreted as an index to the same lookup  ta‐
32       ble. See gl_triangle(3) for more details on shadowing.
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34       gl_wtriangle is used to draw wrapped surfaces with shadowing interpola‐
35       tion. The function gl_swtriangle(3) does it without shadowing.
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37       bitmap1 defines the back side of the triangle, bitmap2 the front.
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39       The bf value is used to tell the routine to draw the backside if it  is
40       facing the other way.  bf tells which way the triangle should be facing
41       to show the front, since you will more than likely require both  combi‐
42       nations.
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44       bf = 2 defines the back to be drawn when the points are arranged clock‐
45       wise, bf = 3 defines the back to be drawn when the points are  arranged
46       counter clockwise, bf = -1 will probably always draw the front.
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48       Beware,  these  functions are not a direct part of the svgalib library.
49       Instead their source is part of svgalib and can be found in the threeD‐
50       kit/  subdirectory of the original svgalib distribution. However, it is
51       not installed in the system by default, s.t. it is  unclear  where  you
52       can find it if your svgalib was installed by some linux distribution.
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54       In  case  of  any such problem, simply get an svgalib distribution from
55       the net. Yo don't need to install it. Just make in the threeDkit/  sub‐
56       directory. As of this writing, svgalib-1.2.12.tar.gz is the latest ver‐
57       sion  and  can  be   retrieved   by   ftp   from   sunsite.unc.edu   at
58       /pub/Linux/libs/graphics  and tsx-11.mit.edu at /pub/linux/sources/libs
59       which will most probably be mirrored by a site close to you.
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61       The functions are defined in the tri.o and triangl.o  files  (or  their
62       resp. sources) which you must link to your program.
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SEE ALSO

66       vgagl(7),  svgalib(7), threedkit(7), gl_striangle(3), gl_swtriangle(3),
67       gl_triangle(3),    gl_trigetcolorlookup(3),    gl_trisetcolorlookup(3),
68       gl_trisetdrawpoint(3), plane(6), wrapdemo(6).
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AUTHOR

72       This  manual  page  was  edited by Michael Weller <eowmob@exp-math.uni-
73       essen.de>. The demos, the initial documentation and the whole threedkit
74       stuff was done by Paul Sheer <psheer@icon.co.za>.
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76       Paper mail:
77              Paul Sheer
78              P O BOX 890507
79              Lyndhurst
80              Johannesburg 2106
81              South Africa
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83       Donations  (by  check  or  postal  order)  will be appreciated and will
84       encourage  further  development  of  this  software.  However  this  is
85       strictly  on  a voluntary basis where this software falls under the GNU
86       LIBRARY GENERAL PUBLIC LICENSE.
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90Svgalib (>= 1.2.11)               2 Aug 1997                   gl_wtriangle(3)
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